TWI721062B - Plasma processing method and plasma processing device - Google Patents

Abstract

This invention aims to control the variation in the tilt of a formed hole together with the wear of a focus ring. The plasma processing device 1 comprises a chamber 10, a mounting table 16, a focus ring 24a, a first electrode plate 36 and a second electrode plate 35. The focus ring 24a is provided around the mounting table 16 so as to surround the mounting surface of the mounting table 16. The first electrode plate 36 is provided over the mounting table 16. The second electrode plate 35 is provided around the first electrode plate 36 so as to surround and insulate from the first electrode plate 36. In a first step, the plasma processing device 1 conducts a predetermined process on a semiconductor wafer W mounted on the mounting table 16 by use of plasma generated in the chamber. Besides, in a second step, the plasma processing device 1 increases the absolute value of a negative DC voltage applied on the second electrode plate 35 in response to the time elapsed in the first step.

Description

Plasma processing method and plasma processing device

Various aspects and embodiments of the present invention relate to plasma processing methods and plasma processing apparatuses.

In the past, there has been known a plasma processing apparatus that uses plasma to perform processing such as etching on a substrate to be processed. In such a plasma processing apparatus, a mounting table arranged inside the chamber places the substrate to be processed and supplies processing gas into the chamber. Furthermore, from the upper electrode disposed above the substrate to be processed so as to face the substrate to be processed on the mounting table, radio frequency electric energy is applied to the chamber, thereby generating plasma of the processing gas in the chamber. Furthermore, predetermined plasma treatments such as etching are performed on the surface of the substrate to be processed by ions or radicals in the plasma. A negative DC voltage is sometimes applied to the upper electrode.

In addition, there is known a plasma processing apparatus in which a ring-shaped conductive member insulated from the upper electrode is provided around the upper electrode (for example, refer to Patent Document 1 below). The conductive member is applied with a negative DC voltage, which is different from the negative DC voltage applied to the upper electrode. [Prior Art Document] [Patent Document]

Patent Document 1: Japanese Patent Application Publication No. 2015-5755

[Problem to be Solved by the Invention] However, in the plasma processing apparatus, a focus ring is provided around the mounting table so as to surround the substrate to be processed placed on the mounting table. The focus ring improves the uniformity of plasma processing such as etching for the substrate to be processed. However, in the plasma processing device, when the plasma processing is repeated, the focus ring is lost. When the focus ring is worn out, the shape of the focus ring changes, and the size relationship between the plasma sheath formed above the focus ring and the plasma sheath formed above the substrate to be processed changes. Therefore, the loss of the focus ring changes the tilt of particles such as ions in the plasma when they enter the substrate to be processed.

When the change in the tilt of the particles such as ions in the plasma enters the substrate to be processed due to the loss of the focus ring, it is not easy to suppress the deviation of the tilt of the hole formed in the substrate to be processed to the predetermined value. Within the specifications. Therefore, we replaced the focus ring before the deviation of the tilt of the hole exceeded the pre-established specification. When the focus ring is frequently replaced, every time the process stops, the output of the process decreases. [The way to solve the problem]

One aspect of the present invention is a plasma processing method in which a plasma processing device executes the first program and the second program, for example. The plasma processing device includes a chamber, a mounting table, a focusing ring, a first upper electrode, and a second upper electrode. The mounting table is provided inside the chamber and has a mounting surface for mounting the substrate to be processed. The focus ring is provided around the mounting table so as to surround the mounting surface. The first upper electrode is arranged above the mounting table so as to face the mounting surface of the mounting table. The second upper electrode is arranged around the first upper electrode so as to surround the first upper electrode, and is insulated from the first upper electrode. In the first procedure, the plasma processing device uses the plasma generated in the chamber to perform predetermined processing on the substrate to be processed placed on the placing surface of the placing table. Furthermore, in the second process, the plasma processing device increases the absolute value of the negative DC voltage applied to the second upper electrode with the elapse of the first process. [Effects of the invention]

According to the various aspects and embodiments of the present invention, it is possible to suppress the fluctuation of the hole tilt accompanying the loss of the focus ring.

[Preferred Mode for Implementing the Invention] In one embodiment of the plasma processing method disclosed in the present invention, the plasma processing device executes the first procedure and the second procedure. The plasma processing device includes a chamber, a mounting table, a focusing ring, a first upper electrode, and a second upper electrode. The mounting table is provided inside the chamber and has a mounting surface for mounting the substrate to be processed. The focus ring is provided around the mounting table so as to surround the mounting surface. The first upper electrode is arranged above the mounting table so as to face the mounting surface of the mounting table. The second upper electrode is arranged around the first upper electrode so as to surround the first upper electrode, and is insulated from the first upper electrode. In the first procedure, the plasma processing device uses the plasma generated in the chamber to perform predetermined processing on the substrate to be processed placed on the placing surface of the placing table. Furthermore, in the second process, the plasma processing device increases the absolute value of the negative DC voltage applied to the second upper electrode with the elapse of the first process.

Furthermore, in one embodiment of the plasma processing method disclosed in the present invention, in the second procedure, the plasma processing device can also determine the negative DC voltage applied to the second upper electrode based on the first data and the second data Absolute value. Among them, the first data shows the inclination angle of the hole near the edge of the processed substrate relative to the elapsed time of the first process, and the second data shows the processed substrate relative to the absolute value of the negative DC voltage applied to the second upper electrode The inclination angle of the hole near the edge.

Furthermore, in one embodiment of the plasma processing method disclosed in the present invention, the second data can also be produced according to the value of each DC voltage applied to the first upper electrode. Moreover, in the second procedure, the plasma processing device can also specify: the second data corresponding to the value of the DC voltage applied to the first upper electrode, and based on the specified second data and the first data, determine the application The absolute value of the negative DC voltage at the second upper electrode.

In addition, the plasma processing device disclosed in the present invention includes a chamber, a mounting table, a focusing ring, a first upper electrode, a second upper electrode, and a control unit in one embodiment. The mounting table is provided inside the chamber and has a mounting surface for mounting the substrate to be processed. The focus ring is provided around the mounting table so as to surround the mounting surface. The first upper electrode is arranged above the mounting table so as to face the mounting surface. The second upper electrode is arranged around the first upper electrode so as to surround the first upper electrode, and is insulated from the first upper electrode. The control unit performs the following control to increase the absolute value of the negative DC voltage applied to the second upper electrode as the processing time for the predetermined processing of the substrate to be processed by the plasma generated in the chamber elapses.

In addition, in one embodiment, the plasma processing device disclosed in the present invention may further include a memory portion, and the memory portion stores: first data showing the vicinity of the edge of the processed substrate relative to the elapsed time of the first process The inclination angle of the hole; and the second data, showing the inclination angle of the hole near the edge of the processed substrate relative to the absolute value of the negative DC voltage applied to the second upper electrode. In addition, the control unit can also read the first data and the second data from the memory unit, and determine the absolute value of the negative DC voltage applied to the second upper electrode based on the read first data and the second data.

In addition, in one embodiment of the plasma processing apparatus disclosed in the present invention, the memory part can also memorize the second data according to the value of each DC voltage applied to the first upper electrode. In addition, the control unit can also specify the second data corresponding to the value of the DC voltage applied to the first upper electrode among the second data stored in the memory unit, and based on the specified second data and the first data, And determine the absolute value of the negative DC voltage applied to the second upper electrode.

In addition, in one embodiment of the plasma processing apparatus disclosed in the present invention, the second upper electrode can also be annular, and the inner peripheral surface of the second upper electrode can also be positioned on the axis of the focus ring as a reference. It is arranged around the first upper electrode in a way that is farther away from the position of the axis than the inner circumferential surface of the focus ring.

Hereinafter, embodiments of the plasma processing method and plasma processing apparatus disclosed in the present invention will be described in detail based on the drawings. In addition, the disclosed invention is not limited by this embodiment.

[Configuration of Plasma Processing Apparatus 1] FIG. 1 is a cross-sectional view schematically showing an example of the general configuration of the plasma processing apparatus 1 as a whole. The plasma processing apparatus 1 in this embodiment is, for example, a capacitive coupling type parallel plate plasma etching apparatus. The plasma processing apparatus 1 has, for example, a substantially cylindrical chamber 10 formed of aluminum whose surface is anodized. The chamber 10 is safety grounded.

At the bottom of the chamber 10, a cylindrical support 14 is arranged with an insulating plate 12 formed of ceramics or the like interposed therebetween. The support table 14 is provided with a mounting table 16 formed of aluminum or the like, for example. The mounting table 16 also functions as a lower electrode.

The top surface of the mounting table 16 is provided with an electrostatic chuck 18, which uses electrostatic force to adsorb and hold the semiconductor wafer W, which is an example of the substrate to be processed. The electrostatic chuck 18 has a structure in which an electrode 20 formed of a conductive film is sandwiched by a pair of insulating layers or insulating sheets. The electrode 20 is electrically connected to a DC power supply 22. The semiconductor wafer W is placed on the top surface 18 a of the electrostatic chuck 18, and is adsorbed and held on the electrostatic chuck 18 by electrostatic forces such as Coulomb force generated by the DC voltage supplied from the DC power supply 22. The top surface 18a of the electrostatic chuck 18 on which the semiconductor wafer W is mounted is an example of the mounting surface of the mounting table 16.

Both the periphery of the electrostatic chuck 18 and the top surface of the mounting table 16 are provided with a conductive member 24b. In addition, the conductive member 24b is provided with a conductive focus ring 24a formed of silicon or the like so as to surround the top surface 18a of the electrostatic chuck 18. The focus ring 24a improves the uniformity of plasma processing such as etching. The side surfaces of the mounting table 16 and the supporting table 14 are provided with a cylindrical inner wall member 26 formed of, for example, quartz.

For example, a ring-shaped refrigerant chamber 28 is formed inside the support base 14. In the refrigerant chamber 28, a refrigerant of a predetermined temperature, such as cooling water, is circulatedly supplied from a cooling unit (not shown) provided outside through the pipes 30a and 30b. The temperature of the support table 14, the mounting table 16, and the electrostatic chuck 18 is controlled by the refrigerant circulating in the refrigerant chamber 28, and the semiconductor wafer W on the electrostatic chuck 18 is controlled to a predetermined temperature.

In addition, heat transfer gas such as He gas from a heat transfer gas supply mechanism (not shown) is supplied between the top surface 18a of the electrostatic chuck 18 and the back surface of the semiconductor wafer W via the pipe 32.

Above the mounting table 16 which functions as a lower electrode, an upper electrode 34 is provided so as to face the mounting table 16. The space between the upper electrode 34 and the mounting table 16 becomes a plasma generation space. The upper electrode 34 forms a surface facing the semiconductor wafer W on the mounting table 16 that functions as a lower electrode and is connected to the plasma generating space, that is, a facing surface.

The upper electrode 34 is supported by the upper part of the chamber 10 via the insulating shielding member 42. The upper electrode 34 has a first electrode plate 36, a second electrode plate 35, and an electrode support 38. The first electrode plate 36 constitutes a surface facing the mounting table 16 and has a plurality of ejection holes 37. The first electrode plate 36 and the second electrode plate 35 are preferably low-resistance conductors or semiconductors with little Joule heat, for example, preferably formed of silicon or SiC. The second electrode plate 35 has a ring shape and is provided around the first electrode plate 36 so as to surround the first electrode plate 36. The second electrode plate 35 is provided at a position above the focus ring 24a. The second electrode plate 35 is insulated from the first electrode plate 36 by the insulating member 39. The first electrode plate 36 is an example of the first upper electrode, and the second electrode plate 35 is an example of the second upper electrode.

FIG. 2 is a top view schematically showing an example of the positional relationship between the focus ring 24a and the second electrode plate 35. FIG. 3 is an enlarged cross-sectional view schematically showing an example of the positional relationship between the focus ring 24a and the second electrode plate 35. FIG. 2 shows the focus ring 24 a and the second electrode plate 35 when viewed from the upper electrode 34 toward the mounting table 16. As shown in FIG. 2, the focus ring 24a and the second electrode plate 35 have an annular shape, and the central axes of the focus ring 24a and the second electrode plate 35 are almost the same. The point o shown in FIG. 2 represents a point through which the central axis of the focus ring 24a and the second electrode plate 35 pass. In this embodiment, the radius r1 of the inner circumferential surface 24c of the focus ring 24a is shorter than the radius r2 of the inner circumferential surface 35a of the second electrode plate 35 as shown in FIGS. 2 and 3, for example. In addition, in other forms, the radius r1 of the inner peripheral surface 24c of the focus ring 24a may be the same length as the radius r2 of the inner peripheral surface 35a of the second electrode plate 35.

Return to Figure 1 to continue the description. The electrode support 38 supports the first electrode plate 36 and the second electrode plate 35 to be freely attachable and detachable. In addition, the electrode support 38 has a water-cooling structure formed of a conductive material such as aluminum whose surface has been anodized. A gas diffusion chamber 40 is provided inside the electrode support 38. A plurality of gas circulation holes 41 that communicate with the ejection holes 37 extend downward from the gas diffusion chamber 40.

The electrode support 38 is formed with a gas inlet 62 for guiding the processing gas to the gas diffusion chamber 40, and a gas supply pipe 64 is connected to the gas inlet 62. The gas supply pipe 64 is connected to a processing gas supply source 66 via a valve 70 and a mass flow controller (MFC; Mass Flow Controller) 68. When etching the semiconductor wafer W, a processing gas for etching is supplied to the gas diffusion chamber 40 from the processing gas supply source 66 through the gas supply pipe 64. The processing gas supplied into the gas diffusion chamber 40 diffuses in the gas diffusion chamber 40 and is sprayed into the plasma processing space in a spray pattern through the respective gas flow holes 41 and the spray holes 37. That is, the upper electrode 34 also functions as a shower head for supplying processing gas into the plasma processing space.

The electrode support 38 is electrically connected to a variable DC power supply 48a via a low-pass filter (LPF; Low-pass filter) 46a and a switch 47a. The variable DC power supply 48a outputs a negative DC voltage whose magnitude (absolute value) is instructed by the control unit 95 to be described later. The switch 47a controls the supply and interruption of the negative DC voltage from the variable DC power supply 48a to the electrode support 38. Hereinafter, there may be cases where the negative DC voltage supplied from the variable DC power supply 48a to the electrode support 38 is referred to as the central DC.

The second electrode plate 35 is electrically connected to a variable DC power supply 48b via an LPF 46b and a switch 47b. The variable DC power supply 48b outputs a negative DC voltage whose magnitude (absolute value) is instructed by the control unit 95 to be described later. The switch 47b controls the supply and interruption of the negative DC voltage from the variable DC power supply 48b to the second electrode plate 35. Hereinafter, there may be cases where the negative DC voltage supplied from the variable DC power supply 48b to the second electrode plate 35 is referred to as edge DC.

From the side wall of the chamber 10, a cylindrical ground conductor 10a is provided above the height position of the upper electrode 34. The ground conductor 10a has a top wall at its upper part.

The mounting table 16 functioning as a lower electrode is connected to a first radio frequency power source 89 via a matching unit 87. In addition, the mounting table 16 is electrically connected to a second radio frequency power source 90 via a matching device 88. The output frequency of the first radio frequency power source 89 is above 27 MHz, for example, 40 MHz. The output frequency of the second RF power source 90 is below 13.56 MHz, for example, 2 MHz.

The matcher 87 matches the impedance of the first RF power source 89 with the load impedance, so that when plasma is generated in the chamber 10, the impedance of the first RF power source 89 and the load impedance are apparently consistent. Similarly, the matcher 88 matches the impedance of the second radio frequency power source 90 with the load impedance, so that when plasma is generated in the chamber 10, the impedance of the second radio frequency power source 90 and the load impedance are apparently consistent.

An exhaust port 80 is provided at the bottom of the chamber 10. An exhaust device 84 is connected to the exhaust port 80 via an exhaust pipe 82. The exhaust device 84 has a vacuum pump such as a turbo molecular pump, and can reduce the pressure in the chamber 10 to a desired degree of vacuum. In addition, the side wall of the chamber 10 is provided with an opening 85 for carrying in and out of the semiconductor wafer W, and the opening 85 can be opened and closed by a gate valve 86.

The inner wall of the chamber 10 is freely detachable and equipped with a deposit barrier 11 to prevent etching by-products (deposits) from adhering to the inner wall of the chamber 10 along the inner wall of the chamber 10. In addition, the deposit barrier 11 is also provided on the outer periphery of the inner wall member 26. An exhaust plate 83 is provided between the deposit barrier 11 on the chamber wall side at the bottom of the chamber 10 and the deposit barrier 11 on the inner wall member 26 side. Regarding the deposit barrier 11 and the exhaust plate 83, for example, those covered with ceramics such as _{Y 2} O _{3 on the aluminum material can be suitably used.}

The portion of the inner wall of the chamber constituting the deposit barrier 11 is almost the same height as the semiconductor wafer W, and a conductive member (GND block) 91 connected to the ground electrode in a DC manner is provided. With the GND block 91, abnormal discharge in the chamber 10 is prevented.

The various components of the plasma processing device 1 are controlled by the control unit 95. The control unit 95 is connected to a user interface 96 composed of the following: a keyboard that allows the program manager to perform command input operations, etc. in order to manage the plasma processing device 1, or to visualize the working status of the plasma processing device 1 The display.

Furthermore, a memory unit 97 is connected to the control unit 95. The storage unit 97 stores control programs for realizing various processes executed in the plasma processing apparatus 1 under the control of the control unit 95, or programs for executing processing of various components of the plasma processing apparatus 1 in accordance with processing conditions, That is, the formula and so on. In addition, the storage unit 97 stores the data of the first table and the second table described later. The memory portion 97 is, for example, a hard disk or a semiconductor memory. In addition, the memory portion 97 may also be a portable memory medium that can be read by a computer. In this case, the control unit 95 obtains the control program stored in the storage medium through a device that reads data from the storage medium. The storage medium is such as CD-ROM or DVD.

The control unit 95 reads an arbitrary recipe from the memory unit 97 and executes it in accordance with instructions from the user via the user interface 96, so as to control the various parts of the plasma processing apparatus 1 and apply a predetermined plasma to the semiconductor wafer W deal with. In addition, the plasma processing apparatus 1 in this embodiment includes a control unit 95, a user interface 96, and a memory unit 97.

In the plasma processing apparatus 1 configured as described above, when performing etching processing on the semiconductor wafer W, the gate valve 86 is first controlled to be in an open state, and the semiconductor wafer W, which is the etching target, is carried into the chamber 10 through the opening 85 , And placed on the electrostatic chuck 18. Furthermore, a predetermined DC voltage is applied from the DC power supply 22 to the electrostatic chuck 18, and the semiconductor wafer W is sucked and held on the top surface 18 a of the electrostatic chuck 18.

Then, the processing gas used for etching is supplied from the processing gas supply source 66 to the gas diffusion chamber 40 at a predetermined flow rate, and the processing gas is supplied into the chamber 10 through the gas flow hole 41 and the ejection hole 37. Furthermore, the inside of the chamber 10 is exhausted by the exhaust device 84, and the pressure in the chamber 10 is controlled to a predetermined pressure. With the processing gas supplied in the chamber 10, the plasma generation radio frequency is applied from the first radio frequency power supply 89 to the mounting table 16 with a predetermined power, and the ion radio frequency is pulled in from the second radio frequency with a predetermined power. The radio frequency power 90 is applied to the mounting table 16. Furthermore, a predetermined magnitude of negative direct current voltage is applied from the variable direct current power source 48a to the electrode support 38, and a predetermined magnitude of negative direct current voltage is applied from the variable direct current power source 48b to the second electrode plate 35.

The processing gas ejected from the ejection hole 37 of the upper electrode 34 is plasma-generated in the glow discharge generated between the upper electrode 34 and the placing table 16 by the radio frequency applied to the placing table 16, and is generated by the plasma The free radicals or ions etch the processed surface of the semiconductor wafer W.

Furthermore, in this embodiment, the control unit 95 controls the variable DC power supply 48b to increase the magnitude of the negative DC voltage applied to the second electrode plate 35 according to the elapsed time of the plasma treatment.

[Relationship between the plasma processing time and the inclination angle of the hole] Here, the relationship between the plasma processing time and the inclination angle of the hole formed on the processed surface of the semiconductor wafer W will be described. FIG. 4 is an explanatory diagram showing the change in the tilt of the ion incident direction accompanied by the loss of the focus ring 24a. When the focus ring 24a is not worn, for example, as shown in FIG. 4(a), the plasma sheath above the focus ring 24a is formed at a higher position than the plasma sheath above the semiconductor wafer W, for example. In this case, in the vicinity of the peripheral portion (edge) of the semiconductor wafer W, ions in the plasma are incident obliquely in the direction of the peripheral portion of the processed surface of the semiconductor wafer W. During etching, holes are formed along the direction of ion incidence. Therefore, the shape in the depth direction of the hole formed near the peripheral edge of the processed surface of the semiconductor wafer W becomes a shape inclined toward the peripheral edge of the processed surface of the semiconductor wafer W with respect to the vertical direction.

After that, the plasma treatment is repeated, and when the focus ring 24a is lost due to the plasma, the height of the focus ring 24a becomes lower as shown in FIG. 4(b), for example. As a result, for example, as shown in FIG. 4(b), the position of the plasma sheath above the focus ring 24a becomes lower, and the position of the plasma sheath formed above the periphery of the semiconductor wafer W becomes more formed. The plasma sheath above and near the center of the semiconductor wafer W is lower. Thereby, in the vicinity of the peripheral portion of the semiconductor wafer W, ions in the plasma are incident obliquely in the direction of the center portion of the processed surface of the semiconductor wafer W. Thereby, the shape in the depth direction of the hole formed near the peripheral edge of the processed surface of the semiconductor wafer W becomes a shape inclined to the center of the processed surface of the semiconductor wafer W with respect to the vertical direction.

Here, the definition of the inclination angle in the depth direction of the hole is explained. Fig. 5 illustrates the definition of the inclination angle of the hole in the embodiment. In the present embodiment, the inclination angle θ of the hole is defined as an angle in the depth direction of the hole opposite to the vertical direction as shown in FIG. 5, for example. For example, as shown in FIG. 5(a), when the hole h1 formed in the semiconductor wafer W is inclined toward the peripheral edge of the processed surface of the semiconductor wafer W, the inclination angle θ of the hole is a positive value. Also, for example, as shown in FIG. 5(b), when the hole h2 formed in the semiconductor wafer W is inclined toward the center of the processed surface of the semiconductor wafer W, the inclination angle θ of the hole is a negative value.

In the example shown in FIG. 4, in the state where the focus ring 24a is not worn out, the focus ring 24a in a shape in which the inclination angle θ of the hole becomes a positive predetermined value (for example, θ=+0.5deg) is set in the chamber 10 . Moreover, as the plasma treatment time elapses, the focus ring 24a is worn out, and the inclination angle θ of the hole decreases. Furthermore, the inclination angle θ of the hole eventually becomes a negative value. After that, as the plasma treatment time elapses, the focus ring 24a is further worn out, and the inclination angle further becomes a larger negative value. Before the inclination angle θ of the hole becomes a predetermined negative angle (for example, θ=−0.5deg), the focus ring 24a is replaced.

[The relationship between the edge DC and the inclination angle θ] Next, the relationship between the edge DC and the inclination angle θ of the hole will be explained. FIG. 6 shows an example of the measurement result of the inclination angle θ of the hole of each combination of the center DC and the edge DC. When referring to the measurement result of FIG. 6, it is known that the greater the absolute value of the negative DC voltage applied to the second electrode plate 35, that is, the edge DC, the more the inclination angle θ of the hole increases in the positive direction. When the absolute value of the negative DC voltage applied to the second electrode plate 35 is increased, for example, as shown in FIG. 7, the plasma sheath above the focus ring 24a moves in the direction of the second electrode plate 35, that is, upward. FIG. 7 shows an example of the position change of the plasma sheath when the absolute value of the negative DC voltage applied to the second electrode plate 35 is increased. Therefore, it is considered that the ion incidence direction inclines toward the peripheral edge portion of the processed surface of the semiconductor wafer W, and the inclination angle θ of the hole formed by the ion incidence inclines toward the positive direction.

Therefore, for example, as shown in Figure 8 (a) and (b), we believe that even if the focus ring 24a is worn out and the position of the plasma sheath becomes lower as the plasma treatment time elapses, it is only necessary to make the When the size (absolute value) of the edge DC of 35 increases, the change in the inclination angle θ of the hole caused by the loss of the focus ring 24a can be suppressed.

[First Table] Next, the method of creating the first table used to determine the value of edge DC will be explained. First, measure the inclination angle θ of the hole relative to the plasma treatment time. For example, actually a plurality of semiconductor wafers W are etched, and the inclination angle θ of the hole formed by the semiconductor wafer W is measured for the semiconductor wafer W of the cumulative time of each plasma processing. In addition, for other examples, the focus ring 24a can also be used to etch the semiconductor wafer W to measure the inclination angle θ of the hole formed by the semiconductor wafer W. The focus ring 24a is It is processed in such a way that the loss amount of the accumulated time of the plasma treatment is reduced and the height is reduced.

From the measurement result of the inclination angle θ of the hole in each plasma processing time, the amount of change in the inclination angle θ in each plasma processing unit time is calculated. When the measured value of the inclination angle θ of the hole in each plasma treatment time is illustrated, it is shown in FIG. 9, for example. FIG. 9 shows an example of the relationship between the plasma treatment time and the inclination angle of the hole. In the example of FIG. 9, the change amount of the tilt angle θ relative to the unit time of plasma treatment is -0.023 deg per ten hours.

In addition, the value of the inclination angle θ is stored in the memory unit 97 as the first table according to the elapsed time of each plasma treatment. FIG. 10 shows an example of the first table 970. The first table 970, for example, as shown in FIG. 10, stores the inclination angle θ972 of the hole and the elapsed time 971 of the plasma treatment. In addition, in the example of FIG. 10, the initial value of the inclination angle θ972 of the hole is 0.50 deg, but the initial value of the inclination angle θ972 of the hole may also be other values such as 0 deg. The first table 970 is an example of the first data.

[Second Table] Next, the method of creating the second table used to determine the value of edge DC will be explained. First, for example, as shown in FIG. 6, the inclination angle θ of the hole is measured according to each combination of the center DC and the edge DC. Furthermore, according to the value of each central DC, the amount of change in the inclination angle θ relative to the voltage change of the edge DC is calculated from the measurement result of the inclination angle θ of the hole opposite to the edge DC. When the measured value of the inclination angle θ of the hole opposite to the edge DC is illustrated, it is shown in FIG. 11, for example. FIG. 11 shows an example of the change of the inclination angle of the hole relative to the voltage change of the edge DC. In the measurement results in Figure 11, the central DC system is -150V. In the example of FIG. 11, the amount of change in the inclination angle θ with respect to the voltage change of the edge DC is 0.007 deg per 10V.

Furthermore, the inclination angle θ is converted into a relative value Δθ calculated from the inclination angle θ corresponding to the initial value of the edge DC. In addition, for each central DC value, the combination of the edge DC and the relative value Δθ is stored as a second table in the memory unit 97. FIG. 12 shows an example of the second table 975. The second table 975, for example, as shown in FIG. 12, stores individual tables 977 according to the voltage value 976 of each central DC. In each individual table 977, the relative value Δθ979 and the voltage value 978 of the edge DC are paired and stored. The second table 975 is an example of the second data.

[Control of Edge DC] FIG. 13 is a flowchart showing an example of the control process of edge DC executed by the plasma processing device 1. In addition, before the flowchart shown in FIG. 13 starts, the semiconductor wafer W is carried into the chamber 10, the processing gas is supplied into the chamber 10, and the pressure in the chamber 10 is controlled to a predetermined pressure. In addition, the negative direct current voltage prescribed by the treatment recipe is applied to the electrode support 38 as the central DC.

First, the control unit 95 controls the variable DC power supplies 48a and 48b to set the edge DC to the same value as the center DC (S100). Thereby, a negative DC voltage of the same magnitude as the negative DC voltage applied to the electrode support 38 is applied to the second electrode plate 35.

Secondly, the control unit 95 controls the first radio frequency power source 89 and the second radio frequency power source 90 to apply a predetermined power of radio frequency to the mounting table 16 respectively. Thereby, a plasma of the processing gas is generated in the chamber 10, and the generated plasma is used to start the plasma processing of the semiconductor wafer W (S101).

Next, the control unit 95 initializes the elapsed time t to 0 (S102), where this elapsed time represents the cumulative time of plasma processing. In addition, the control unit 95 initializes the time t0 with a predetermined time Δt (S103), and this time t0 indicates the timing of updating the edge DC. The predetermined time Δt is ten hours, for example.

Next, the control unit 95 determines whether the elapsed time t has reached the time t0 (S104). When the elapsed time t has not reached the time t0 (S104: No), the control unit 95 executes the processing shown in step S112.

On the other hand, when the elapsed time t has reached the time t0 (S104: Yes), the control unit 95 refers to the first table 970 in the memory unit 97 to specify the inclination angle θ paired with the current elapsed time t (S105 ). Furthermore, the control unit 95 calculates the difference Δθm (S106): the specifically designated inclination angle θ; and the predetermined inclination angle θ0. The predetermined inclination angle θ0 is the inclination angle that becomes the reference. In this embodiment, the inclination angle θ0 is, for example, +0.5 deg.

Next, the control unit 95 refers to the second table 975 in the memory unit 97, and specifically specifies the individual table 977 to be paired with the value of the central DC applied to the electrode support 38 (S107). Furthermore, the control unit 95 uses the specified individual table 977 to specify the relative value Δθ that is closest to the difference Δθm calculated in step S106 (S108).

Next, the control unit 95 refers to the individual table 977, and specifically specifies the voltage value of the edge DC that is paired with the relative value Δθ specified in step S108 (S109). Furthermore, the control unit 95 controls the variable DC power supply 48b to output a negative DC voltage of a specified voltage value. Thereby, the negative DC voltage of the voltage value specified in step S109 is applied to the second electrode plate 35 (S110).

Next, the control unit 95 adds a predetermined time Δt to the time t0 indicating the timing of updating the edge DC (S111), and determines whether to end the plasma processing (S112). In the case where the plasma processing is not ended (S112: No), the control unit 95 executes the processing shown in step S104 again. On the other hand, in the case of ending the plasma processing (S112: Yes), the plasma processing apparatus 1 ends the control processing of the edge DC shown in this flowchart.

In the foregoing, one embodiment of the present invention has been described. As is clear from the above description, according to the plasma processing apparatus 1 of the present embodiment, it is possible to suppress the fluctuation in the tilt of the hole caused by the loss of the focus ring 24a.

In addition, the technology disclosed in the present invention is not limited to the above-mentioned embodiment, and various modifications can be made within the scope of the subject matter.

For example, in the above embodiment, the upper electrode 34 is provided with a first electrode plate 36 and a second electrode plate 35, and the second electrode plate 35 is applied with a negative DC voltage that is independently controlled from the negative DC voltage applied to the first electrode plate 36. DC voltage. However, the technology disclosed in the present invention is not limited to this. For example, the second electrode plate 35 may also be composed of a plurality of ring-shaped members in the radial direction, and the negative DC voltage applied to each ring-shaped member is independently controlled. Thereby, the distribution of the sheath on the periphery of the semiconductor wafer W can be controlled more accurately.

In addition, in the above-mentioned embodiment, the plasma processing apparatus 1 for etching the semiconductor wafer W using plasma is taken as an example, but the technology disclosed in the present invention is not limited to this. As long as it is a device that uses plasma for processing, even in a film forming device, or a device that uses plasma to modify the film laminated on the semiconductor wafer W, the above-mentioned edge DC control can be used.

As mentioned above, the present invention has been explained using the embodiments, but the technical scope of the present invention is not limited to the scope described in the above-mentioned embodiments. Those having ordinary knowledge in the field to which the present invention pertains can obviously add various changes or improvements to the above-mentioned embodiments. In addition, it can be understood from the scope of the patent application that the technical scope of the present invention also includes the forms added with the above-mentioned changes or improvements.

r1, r2‧‧‧radius W‧‧‧Semiconductor Wafer 1‧‧‧Plasma processing device 10‧‧‧Chamber 10a‧‧‧Grounding conductor 11‧‧‧Sediment barrier 12‧‧‧Insulation board 14‧‧‧Support Desk 16‧‧‧Mounting table 18‧‧‧Electrostatic chuck 18a‧‧‧Top surface 20‧‧‧electrode 22‧‧‧DC power supply 24a‧‧‧Focusing Ring 24b‧‧‧Electrical components 24c‧‧‧Inner peripheral surface 26‧‧‧Inner wall components 28‧‧‧Refrigerant Room 30a, 30b‧‧‧Piping 32‧‧‧Piping 34‧‧‧Upper electrode 35‧‧‧Second electrode plate 35a‧‧‧Inner peripheral surface 36‧‧‧First electrode plate 37‧‧‧Spit hole 38‧‧‧Electrode support 39‧‧‧Insulating member 40‧‧‧Gas diffusion chamber 41‧‧‧Gas circulation hole 42‧‧‧Insulating shielding member 46a, 46b‧‧‧Low-pass filter (LPF; Low-pass filter) 47a, 47b‧‧‧switch 48a, 48b‧‧‧Variable DC power supply 62‧‧‧Gas inlet 64‧‧‧Gas supply pipe 66‧‧‧Processing gas supply source 68‧‧‧Mass Flow Controller (MFC; Mass Flow Controller) 70‧‧‧valve 80‧‧‧Exhaust port 82‧‧‧Exhaust pipe 83‧‧‧Exhaust plate 84‧‧‧Exhaust device 85‧‧‧Open 86‧‧‧Gate Valve 87、88‧‧‧matcher 89‧‧‧First Radio 90‧‧‧Second RF 91‧‧‧GND block 95‧‧‧Control Department 96‧‧‧User Interface 97‧‧‧Memory Department 970‧‧‧First Form 971‧‧‧Elapsed time 972‧‧‧Inclination angle θ 975‧‧‧Second Table 976‧‧‧The voltage value of the central DC 977‧‧‧Individual Table 978‧‧‧Edge DC voltage value 979‧‧‧relative value Δθ S100~S112‧‧‧Step

FIG. 1 is a cross-sectional view schematically showing an example of the schematic configuration of the entire plasma processing apparatus. FIG. 2 is a top view schematically showing an example of the positional relationship between the focus ring and the second electrode plate. FIG. 3 is an enlarged cross-sectional view schematically showing an example of the positional relationship between the focus ring and the second electrode plate. Figure 4 (a) (b) is used to illustrate the change in the tilt of the ion incident direction accompanied by the loss of the focus ring. Figure 5 (a) (b) illustrates the definition of the inclination angle of the hole in the embodiment. Fig. 6 shows an example of the measurement result of the inclination angle θ of the hole of each combination of the central DC (Direct Current) and the edge DC. FIG. 7 shows an example of the position change of the plasma sheath when the absolute value of the negative DC voltage applied to the second electrode plate is increased. Fig. 8(a)(b) is used to illustrate the tilt of the ion incident direction accompanied by the loss of the focus ring in this embodiment. FIG. 9 shows an example of the relationship between the plasma treatment time and the inclination angle of the hole. Figure 10 shows an example of the first table. FIG. 11 shows an example of the change of the inclination angle of the hole relative to the voltage change of the edge DC. Figure 12 shows an example of the second table. FIG. 13 is a flowchart showing an example of edge DC control processing executed by the plasma processing device.

W‧‧‧Semiconductor Wafer

1‧‧‧Plasma processing device

10‧‧‧Chamber

10a‧‧‧Grounding conductor

11‧‧‧Sediment barrier

12‧‧‧Insulation board

14‧‧‧Support Desk

16‧‧‧Mounting table

18‧‧‧Electrostatic chuck

18a‧‧‧Top surface

20‧‧‧electrode

22‧‧‧DC power supply

24a‧‧‧Focusing Ring

24b‧‧‧Electrical components

26‧‧‧Inner wall components

28‧‧‧Refrigerant Room

30a, 30b‧‧‧Piping

32‧‧‧Piping

34‧‧‧Upper electrode

35‧‧‧Second electrode plate

36‧‧‧First electrode plate

37‧‧‧Spit hole

38‧‧‧Electrode support

39‧‧‧Insulating member

40‧‧‧Gas diffusion chamber

41‧‧‧Gas circulation hole

42‧‧‧Insulating shielding member

46a, 46b‧‧‧Low-pass filter (LPF; Low-pass filter)

47a, 47b‧‧‧switch

48a, 48b‧‧‧Variable DC power supply

62‧‧‧Gas inlet

64‧‧‧Gas supply pipe

66‧‧‧Processing gas supply source

68‧‧‧Mass Flow Controller (MFC; Mass Flow Controller)

70‧‧‧valve

80‧‧‧Exhaust port

82‧‧‧Exhaust pipe

83‧‧‧Exhaust plate

84‧‧‧Exhaust device

85‧‧‧Open

86‧‧‧Gate Valve

87、88‧‧‧matcher

89‧‧‧First Radio

90‧‧‧Second RF

91‧‧‧GND block

95‧‧‧Control Department

96‧‧‧User Interface

97‧‧‧Memory Department

Claims (6)

A plasma processing method, which is executed by a plasma processing device, the plasma processing device comprising: a chamber; a mounting table, which is arranged inside the chamber and has a mounting surface for mounting a substrate to be processed; A focusing ring is arranged around the mounting table so as to surround the mounting surface; a first upper electrode is arranged above the mounting table so as to face the mounting surface; and a second upper electrode is disposed to surround the mounting surface. The first upper electrode is arranged around the first upper electrode and insulated from the first upper electrode; the plasma processing method includes: a first procedure, using the plasma generated in the chamber, and The substrate to be processed on the mounting surface is subjected to a predetermined process; the second process, with the elapse of the first process, increases the absolute value of the negative DC voltage applied to the second upper electrode to suppress the formation of The variation of the inclination angle of the hole near the edge of the substrate to be processed is caused by the wear of the focus ring; the plasma processing device is used to memorize the first data and the second data, and the first data is displayed The inclination angle of the hole relative to the elapsed time of the first procedure, and the second data shows the inclination angle of the hole relative to the absolute value of the negative DC voltage applied to the second upper electrode; and In the second procedure, the plasma processing device is used to determine the absolute value of the negative DC voltage applied to the second upper electrode based on the first data and the second data. For example, the plasma processing method of claim 1, wherein memorizing the second data includes memorizing the second data for each value of the DC voltage applied to the first upper electrode, and determining the value applied to the second upper electrode The absolute value of the negative DC voltage of the upper electrode includes: in the second program, the plasma processing device specifies the second data corresponding to the value of the DC voltage applied to the first upper electrode, and the plasma processing device The absolute value of the negative DC voltage applied to the second upper electrode is determined based on the specified second data and the first data. For example, the plasma processing method of the first item in the scope of the patent application, wherein the first procedure includes applying a first negative direct current voltage to the first upper electrode, and applying a second negative direct current voltage to the second upper electrode, the second negative The DC voltage has the same magnitude as the first negative DC voltage; and the second procedure includes increasing the absolute value of the second negative DC voltage when the elapsed time has reached a predetermined time. A plasma processing device, which is characterized by comprising: a chamber; a mounting table, which is arranged inside the chamber and has a mounting surface for mounting a substrate to be processed; and a focusing ring, which is arranged on the mounting surface so as to surround the mounting surface. Around the mounting table; the first upper electrode is arranged above the mounting table in a manner facing the mounting surface; The second upper electrode is arranged around the first upper electrode in such a way as to surround the first upper electrode, and is insulated from the first upper electrode; the control part controls to: The slurry applies a predetermined treatment to the substrate to be processed placed on the placement surface; and as the predetermined treatment elapses, the absolute value of the negative DC voltage applied to the second upper electrode increases to suppress The variation of the inclination angle of the hole formed near the edge of the substrate to be processed, the variation being caused by the wear of the focus ring; and the memory part, which memorizes: the first data showing the relative elapsed time of the predetermined processing The inclination angle of the hole; and a second data showing the inclination angle of the hole relative to the absolute value of the negative DC voltage applied to the second upper electrode, wherein the control unit reads the first data from the memory unit And the second data, and based on the read first data and the second data, determine the absolute value of the negative DC voltage applied to the second upper electrode. For example, the plasma processing device of claim 4, wherein the memory portion stores the second data for each value of the DC voltage applied to the first upper electrode, and the control portion stores the second data in the memory portion The second data specifically specifies the second data corresponding to the value of the DC voltage applied to the first upper electrode, and based on the specifically designated second data and the first data, it is determined to be applied to the second The absolute value of the negative DC voltage of the upper electrode. For example, the plasma processing device of item 4 or 5 of the scope of patent application, wherein the second upper electrode is annular, The second upper electrode is arranged on the first upper part in such a way that the inner peripheral surface of the second upper electrode is positioned at a position farther from the axis than the inner peripheral surface of the focus ring as the reference to the axis of the focus ring Around the electrode.

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